Alkan-1-al-7-ols

ABSTRACT

Alkyl substituted alkan-1-al-7-ols and their production by reaction of alk-1-en-6-ols in the presence of rhodium and iridium catalysts with carbon monoxide and hydrogen at from 50*C to 200*C and 100 to 1,500 atmospheres.

United States Patent 1 Himmele et al.

[ Nov. 11, 1975 4] ALKAN-l-AL-7-0LS [22] Filed: Dec. 17, I970 [2|] Appl.No.: 99,308

[30] Foreign Application Priority Data Dec. 24, 1969 Germany .,962.8

[52] US. Cl. 260/602; 252/522 [51] Int. Cl. C07C 47/19 [58] Field ofSearch 260/602 [56] References Cited UNITED STATES PATENTS 3,239,5663/[966 Slaugh et aI 4. 260/610 B X 8/1969 Blumenthal 260/602 X 7/I97OSaucy 260/602 X FOREIGN PATENTS OR APPLICATIONS 927.946 5/1955 GermanyPrimar v Evamt'ner-Richard J. Gallagher Assistant Examiner-D. B.Springer Attorney, Agenl, or Firmlohnston, Keil, Thompson & ShurtIeff[57] ABSTRACT AlkyI substituted alkan-I-aI-7-ols and their production byreaction of aIk-I-en-6-0Is in the presence of rhodium and iridiumcatalysts with carbon monoxide and hydrogen at from 50C to 200C and 100to L500 atmospheres.

4 Claims, No Drawings ALKAN-l-AL-7-0LS The present invention relates toa new process for the production of a1kan-l-al-7-ols having the formula(I):

in which R and R each denotes methyl or ethyl, R and R each denoteshydrogen or methyl, and R denotes hydrogen or alkyl having one to sixcarbon atoms.

[t is known that the important perfume 3,7-dimethyloctan-l-al-7-ol(hydroxycitronellal) can be prepared in a two-stage synthesis from thenatural substance citronellal or in a multistage process starting from2-dehydrolina1ool. These methods or preparation are howeverunsatisfactory in many respects, such as the necessity of starting fromexpensive natural substances, the expensive and cumbersome nature of theprocesses involving a large number of stages, or the impossibility ofapplying them to the production of homologous compounds.

The invention therefore has as its object to make hydroxycitronellalmore readily availably and to make its homologs accessible for the firsttime.

We have found that alkan-l-a1-7-ols having the general formula (I) areobtained in a notable reaction by reacting an alk-l-en-6-ol having thegeneral formula ([1):

in the presence of a rhodium or iridium catalyst at from 50 to 200C and100 to 1,500 atmospheres with carbon monoxide and hydrogen.

The starting compounds ([1) may be obtained in the following manner:(see U.S. application Ser. No. 99,307). When R is hydrogen, they areobtained by reduction of 2-methylhep-l-en-6-one or appropriatederivatives thereof, and when R is alkyl as defined they are obtainedsimilarly in a known manner by reaction of this methylheptenone with anorganometallic compound, for example a Grignard compound. The followingare examples of starting compounds ([1): Z-methylhept-l-en-6-ol,2-ethylhept-l-en-6-ol, 2,3-dimethylhept-l-en-6-ol,2,6-dimethylhept-l-en-6-o1, 2,3,6- trimethylheptl -en-6-0l, 2,5,o-trimethylheptl -en-6-o1, 2-ethyl-3-methylhept-l-en-6-ol,2-ethyl-5-methylheptl-en-6-ol, 2,6-dimethyloct-1-en-6-o1,2,3,6-trimethyloctl -en-6-ol, 2,5,6-trimethyloct-l -en-6-ol, 2-methyl-6-ethyloct-l-en-6-ol, 2,3-dimethyl-6-ethyloct- 1-en-6-ol,2,5'dimethyl-6-ethyloct-l-en-6-ol, 2-ethyl-6- methyloct- I -en-6-ol,2-ethyl-3,6-dimethyloct-1-en-6- ol, 2-ethyl-5,6-dimethy1octl-en-6-ol,2,6-diethyloct-l en-6-o1, 2,6-diethyl-3-methyloct-1-en-6-o1,2,6-diethyl- S-methyloct- 1 -en-6-ol, 2,6,7-trimethyloctl -en-6-ol, andthe corresponding derivatives of non-l-en-6-ol, deca-l-en--ol,undeca-l-en--ol and dodeca-l-en-6- 01. Starting compounds having theformula (II) in which R and R denote methyl and R denotes hydrogen suchas 2-methylhept-1-en-6-ol, 2,3-dimethylheptl-en-6-ol, 2,6-dimethy1heptl-en-6-ol, 2,3,6-trimethylhept-1-en-6-ol and the correspondingderivatives of oct-l-en-G-ol and 2,6,7-trimethyloct-1-en-6-ol haveproved to be particularly useful.

The reaction according to the invention resembles in procedure the knownhydroformylation or 0x0 synthetis (hereby incorporated by reference: J.Falbe: Synthesen mit Kohlenmonoxid," Springer-Verlag, 1967, pp. 3 to72). In spite of the same measures, the present method is a veryremarkable variant having regard to the result of the reaction. Contraryto expectation supported by many literature references, the formyl groupenters almost exclusively into the l-position of the lolefin (11) andnot into the 2-position.

Finely divided (particularly powdered) metallic rhodium, rhodiumcarbonyls, rhodium chloride, rhodium nitrate, rhodium sulfate, dirhodiumtetracarbonyl dichloride and the complex compounds which are obtained byreaction of rhodium salts or rhodium carbonyl compounds with triphenylphosphine, olefins or diolefins are suitable as catalysts for thehydroformylation reaction. Corresponding iridium catalysts may be usedinstead of the rhodium catalysts. The amount of catalyst may be 0.0000]to 1 percent, preferably from 0.0001 to 0.01 percent, by weight ofrhodium or iridium based on the starting compound (11). Smaller amountsretard the reaction too much and larger amounts do not accelerate thereaction very much.

Carbon monoxide and hydrogen are preferably used in about equimolaramounts, but it is possible to use an excess of up to about four timesthe molar amount of either of the gases.

The hydroformylation is preferably carried out at from to 150C and atotal pressure of 300 to 1,000 atmospheres of carbon monoxide andhydrogen in an inert solvent or diluent such as benzene, toluene,mixtures of xylenes, naphtha, ethers or esters.

The reaction mixture may be worked up into the product (I) by knownmethods, for example by fractional distillation at subatmosphericpressure.

The alkan-1-al-7-ols obtainable according to the invention are valuableodorants and, by reason of this property, have a wide variety ofapplications in perfumery and cosmetics and in improving the odor ofindustrial products such as detergents, glues, polymer dispersions andthe like.

The following Examples illustrate the invention.

EXAMPLE 1 3,7-dimethyloctan-1-al-7-o1 (hydroxycitronellal):

A solution of 1083 g of 2,6-dimethy1hept-l-en-6-o1, 1083 g of benzeneand 120 mg of the rhodium compound (cycloocta-l ,4-diene-RhCl),is heatedfor five hours at l00"C at a pressure of 700 atmospheres of an equimolarmixture of carbon monoxide and hydrogen and the reaction mixture isworked up by fractional distillation at subatmospheric pressure. Thepure product of the process is obtained in a yield of 90 percent.Boiling point: C at 0.03 mm; n, 1.4462.

EXAMPLES 2 to 5 By the method described in Example 1, the following areobtained:

EXAMPLE 2 3,4,7-trimethyloctan-l-al-7-ol from 2,3,6-trimethylhept-l-en-6-ol in a 70% yield; boiling point: 92 to 96C at 0.7 mm; n l.45l l;odor: cyclamen with a note resembling menthol.

EXAMPLE 3 3 ,7 -dimethylnonanl -al-7-ol from 2,6-dimethyloctl en-6-ol ina yield of 85 percent; boiling point: 89 to 9lC at 0.7 mm; n =l 4513;odor: fresh fruity smell reminiscent of oranges and mandarins.

EXAMPLE 4 3,7,8-trimethylnonan-l-al-7-ol from2,6,7-trimethyloct-l-en-G-ol in a yield of 55 percent; boiling point 94Cat 0.45 mm; n 1.4564; odor: fruity note reminiscent of apricots.

EXAMPLE 5 phine is heated for five hours at 100C under a pressure of 700atmospheres of an equimolar mixture of carbon monoxide and hydrogen andthen worked up by distillation. The pure product is obtained in a yieldof percent.

We claim:

1 3 ,4,7 -trimethyloctanl -al-7 -ol.

2. 3,7-dimethylnonan-l-al-7-ol.

3. 3,7,8-trimethylnonan-l-al-7-ol.

4. 3-methyloctanl -al-7-ol.

* II I F i

1. 3,4,7-TRIMETHYLOCTAN-1-AL-7-OL.
 2. 3,7-DIMETHYLNONAN-1-AL-7-OL. 3.3,7,8-TRIMETHYLNONAN-1-AL-7-OL.
 4. 3-METHYLOCTAN-1-AL-7-OL.